buenos diaz

Hello,
I just purchased a new to me 97 Tahoe, 4WD, 5.7, that runs very well but has a few annoying problems that I can't seem to solve. I have used the search function but have had no luck finding a solution.

1. The speedometer reads 20% too fast (reads 50 mph when I am actually going 50 mph, gps confirmed) but the odometer and tripmeter are only 2.5% off (checked against my 'burb). I thought it would need a recalibration but since the odometer and tripmeter are close I'm not sure what is wrong.

2. The dome light stays on intermittently. I have cleaned the contacts and checked the pin switches (replaced drivers door). When it stays on the dome light override switch has no effect. If I pull the #3 fuse and wait a few minutes to replace, it will work for up to 24 hours.

Thanks in advance for any help and insight you can provide. This Tahoe is a father/son project that I will end up being my sons next year. I'm hoping to solve these little problems before he takes over. I would rather him spend his money upgrading rather than fixing little problems.

Thanks again,
Buenos

adam86107

Did you check and make sure the door pins show an OL with the door pins engaged? Maybe one of them is sticking? Could also be an issue with your BCM.

buenos diaz

Thanks for the quick response. What does "OL" mean? Open Line? I thought if it was an intermittent switch it would also show up when driving. I just put 600 miles on it and had no problems during the drive. It only happens after I get out of the Tahoe.

For example, the light is off. I open the door to get out. The lights turn on. I shut the door. Light stays on like it is supposed to. Lock the doors with the fob. Light Stays on.

It also happens when I get in. However, in this case the light stays on after I start the car.

The driver's door switch is brand new.

Thanks again,
Buenos

adam86107

Oh ok, I must have misunderstood. Here are some schematics for ya that might help.

buenos diaz

Thanks, those schematics are a big help!

buenos diaz

Also, the chime for the keys left in the ignition or the headlamps left on works perfectly even when the dome lights stay on. This leads me to believe it is an issue with a relay or something else.

The lights never come on on their own, like there might be a loose connection. They only stay on once they come on due to a door being opened, like a sticking relay.

Thanks,
Buenos

adam86107

I forgot to add those are 99 schematics, I imagine they are the same for the 97.

legolas894

I had a similar issue with the courtesy lights coming on. Turned out to be a short behind the dash. Move your hand up underneath and wiggle the harnesses around and see if you can make the lights come on when they are off. I don't think you have a Body Control Module (my '98 doesn't) but there is another type of module that controls a lot of the lighting. Start wiggling!

buenos diaz

Thanks for the response. I'll give that a try.

Anyone, have a guess as to why the speedo is 20% off but the odometer is only 2.5% off?

Thanks again,
Buenos

adam86107

Does it have oversized tires on it?